STRUCTURAL FATIGUE UNDER NON-STATIONARY RANDOM LOADING

In this paper the problem is examined of estimating the liability of structures to fatigue failure when subjected to non-stationary random loading processes. An analytic expression is deduced for the expected number of crossings per second with positive slope at any amplitude level for a normal non-stationary random process and this result is combined with the cumulative damage hypothesis to give an estimate of the mean damage in a given time for a structure with a normally distributed stress process. In the stationary case’the expressions given here reduce to results already available in the literature